1. Field of the Invention
The present invention relates to a coordinate position detecting apparatus, and a control method and program thereof.
2. Background Art
An example of a coordinate position detecting apparatus for an optical type touch panel or the like is an apparatus using a coordinate position detecting method disclosed in, for instance, JP-A-2001-306241.
This coordinate position detecting apparatus detects the position on the coordinates on the display screen of a display apparatus, such as a plasma display panel or a cathode-ray tube, which is touched with a finger, a pen or the like. The coordinate position detecting apparatus scans the two-dimensional display screen in the horizontal direction (X axis direction) and the vertical direction (Y axis direction) perpendicular to each other, with detection beams; respectively, and detects a position of a light shielding article touched on the display screen in correspondence to a scanning position of a light-shielded detection beam.
FIG. 1 is a diagram for explaining a conventional coordinate position detecting method. A plurality of light emitting elements Ax1 to Axn and Ay1 to Aym are respectively arrayed on one lateral side (X axis direction) and one longitudinal side (Y axis direction) of a display screen 10, and a plurality of light receiving elements Bx1 to Bxn and By1 to Bym are respectively arrayed on the other lateral side and longitudinal side opposite to the light emitting elements.
A scanning operation with detection beams mentioned in this specification is to sequentially turn ON a plurality of light emitting elements Ax1 to Axn and Ay1 to Aym in this order, and receive the detection beams at the opposing light receiving elements. When an arbitrary point P on the display screen 10 is touched with a finger, a pen or so, detection beams emitted from corresponding light emitting elements on the lateral side and the longitudinal side are shielded, and are not received by the opposing light receiving elements, respectively. Accordingly, the touched position is specified by detecting the X-axis and Y-axis coordinate positions of the touched position from the layout positions of those light receiving elements on the lateral side and longitudinal side which have not received the beams.
Data of the coordinate positions detected by the coordinate position detecting method are connected by lines based upon application software installed on a personal computer or the like, and are drawn on the display screen. In the scanning operation with the detection beams, as shown in FIG. 2, the light emitting elements correspond one to one to the light receiving elements, and the loci of the detection beams have a grid pattern.
As a consequence, the coordinate position detecting method that provides grid-shaped loci of detection beams as shown in FIG. 2 cannot acquire coordinate positional information with finer pitches than the layout pitches (arranging intervals) of the light emitting elements and the light receiving elements. If the numbers of the light emitting elements and the light receiving elements are increased so as to make the layout pitches narrower in order to acquire coordinate position information with finer pitches, a large number of elements are required, so that manufacturing cost is increased. Further, the layout pitches are limited to the sizes of the elements (light emitting elements and light receiving elements).
As the conventional coordinate position detecting method cannot acquire coordinate positional information with finer pitches, it is difficult to accurately trace and draw the locus of a finger or a pen touching the display screen.
While the coordinate position detecting method described in JP-A-2001-306241 performs the scanning operation in the limited area, the position of a finger, a pen or so moves out of the scanning range when the moving speed of the finger or the pen is fast, which may result in discontinuous draw lines to be drawn on the display screen.